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authorRussell King - ARM Linux <linux@arm.linux.org.uk>2012-03-06 22:36:07 +0000
committerVinod Koul <vinod.koul@linux.intel.com>2012-03-13 11:37:33 +0530
commit2a926e46022ad7a03e0ac167d8c2b0d88c12c5a8 (patch)
tree7e31a02d6e6d90571d6dd88ebf31db2e5ca8d5c0 /drivers/dma/ppc4xx/adma.c
parentd3ee98cdcd6198ea1cf75c603178acc8a805b69b (diff)
downloadop-kernel-dev-2a926e46022ad7a03e0ac167d8c2b0d88c12c5a8.zip
op-kernel-dev-2a926e46022ad7a03e0ac167d8c2b0d88c12c5a8.tar.gz
dmaengine: fix cookie handling in iop-adma.c and ppc4xx/adma.c
Dan Williams said: > > Russell King wrote: > > Firstly, we have DMA_MIN_COOKIE which has value 1 - so any cookies below > > that aren't valid.  That seems sane. > > > > We seem to have different behaviours: > > > > -       cookie = c->cookie; > > -       cookie++; > > -       if (cookie < 0) > > -               cookie = 1; > > -       c->cookie = cookie; > > -       tx->cookie = cookie; > > > > c->cookie here is initialized to zero, so the first cookie given out will > > be 1.  This is how most DMA engine drivers implement this. > > > > Then we have this: > > > >                cookie = chan->common.cookie; > >                cookie++; > >                if (cookie <= 1) > >                        cookie = 2; > > > >                /* initialize the completed cookie to be less than > >                 * the most recently used cookie > >                 */ > >                chan->common.completed_cookie = cookie - 1; > >                chan->common.cookie = sw_desc->async_tx.cookie = cookie; > > > > Again, chan->common.cookie starts off at 0.  The first cookie given out > > will be 2, and 1 will never be used.  There are three drivers which > > implement it this way. > > > > Why is there this difference, and can these three be corrected to behave > > the same way as the first (and therefore the assignment of cookies > > consolidated?) > > Yes, they should be consolidated, and I believe they have drifted only > because there were no good common helpers and murphy's law took over. So lets fix this up to use the common dma_cookie_assign() helper. Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk> Tested-by: Linus Walleij <linus.walleij@linaro.org> Reviewed-by: Linus Walleij <linus.walleij@linaro.org> Acked-by: Jassi Brar <jassisinghbrar@gmail.com> [imx-sdma.c & mxs-dma.c] Tested-by: Shawn Guo <shawn.guo@linaro.org> Signed-off-by: Vinod Koul <vinod.koul@linux.intel.com>
Diffstat (limited to 'drivers/dma/ppc4xx/adma.c')
-rw-r--r--drivers/dma/ppc4xx/adma.c6
1 files changed, 1 insertions, 5 deletions
diff --git a/drivers/dma/ppc4xx/adma.c b/drivers/dma/ppc4xx/adma.c
index 86239ea..9752062 100644
--- a/drivers/dma/ppc4xx/adma.c
+++ b/drivers/dma/ppc4xx/adma.c
@@ -4022,16 +4022,12 @@ static void ppc440spe_chan_start_null_xor(struct ppc440spe_adma_chan *chan)
async_tx_ack(&sw_desc->async_tx);
ppc440spe_desc_init_null_xor(group_start);
- cookie = chan->common.cookie;
- cookie++;
- if (cookie <= 1)
- cookie = 2;
+ cookie = dma_cookie_assign(&sw_desc->async_tx);
/* initialize the completed cookie to be less than
* the most recently used cookie
*/
chan->common.completed_cookie = cookie - 1;
- chan->common.cookie = sw_desc->async_tx.cookie = cookie;
/* channel should not be busy */
BUG_ON(ppc440spe_chan_is_busy(chan));
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